1. Field of the Invention
The present invention relates to a process for producing a zeolite film, and a zeolite film obtained by the producing process.
2. Description of Related Art
There are present a large number of kinds (types) of zeolites having different crystal structures, for example, LTA, MFI, MOR, FER, FAU and DDR. It is known that, for example, the deca-dodecasil 3R (DDR) type zeolite is formed by a polyhedron containing a main component of silica and including pores made of eight-membered ring oxygen and having pore diameters of 4.4×3.6 angstroms. Since the DDR type zeolite has such small pore diameters, it is possible to selectively adsorb comparatively small molecules of carbon dioxide (CO2), methane (CH4) and ethane (C2H6), so that use applications of the zeolite are expected to be a gas separation film which can selectively separate these molecules, an adsorber, and the like.
There is known a method in which a raw material solution, where zeolite powder which becomes seed crystals, is dispersed, and an appropriate support material for forming a film are placed into a container or the like to carry out hydrothermal synthesis (Patent Document 1). Moreover, as a method of loading seed crystals onto the surface of a support and carrying out hydrothermal synthesis to produce a zeolite film which does not have any defect and which has an even thickness, there is known a method of filtering a slurry containing the seed crystals through a porous support (Patent Documents 2 and 3).